Dump truck with valve control for the tail gate



Oct. 4, 1955 L. s. WOOD DUMP TRUCK WITH VALVE CONTROL FOR THE TAIL GATE7 Sheets-Sheet 1 Original Filed July 25, 1951 AIIHHHI mu /0 III II I'INVENTOR Z 0(//J J. W000,

ATTORNEY Oct. 4, 1955 DUMP TRUCK WITH Original Filed July 25, 1951 7Sheets-Sheet 2 Oct. 4, 1955 L. s. WOOD 2,719,637

DUMP TRUCK WITH VALVE CONTROL FOR THE TAIL GATE Original Filed July 25,1951 7 Sheets-Sheet 3 INVENTOR [aw/J 5. W000,

ATTORNEY Oct. 4, 1955 s. WOOD DUMP TRUCK WITH VALVE CONTROL FOR THE TAILGATE 7 Sheets-Sheet 4 Original Filed July 25 1951 INVENTOR .4 ou/s .5.14 000,

BY viluw maawm ATTORN EY L. s. WOOD 2,719,637

DUMP TRUCK WITH VALVE CONTROL FOR THE TAIL GATE '7 Sheets-Sheet 5 Oct.4, 1955 Original Filed July 25, 1951 INVENTOR ATTORNEY Oct. 4, 1955 L.s. WOOD 2,719,637

DUMP TRUCK WITH VALVE CONTROL FOR THE TAIL GATE Original Filed July 25,1951 7 Sheets-Sheet 6 Oct. 4, 1955 L. 5. W000 DUMP TRUCK WITH VALVECONTROL FOR THE TAIL GATE 7 Sheets-Sheet '7 Original Filed July 25, 1951LOU/S 5. WOOD BY QA IL ATTORNEY United States Patent DUMP TRUCK WITHVALVE CONTROL FOR THE TAIL GATE Original application July 25, 1951,Serial No. 238,443,

now Patent No. 2,683,545, dated July 13, 1954. Divided and thisapplication September 21, 1953, Serial No. 381,421

4 Claims. (Cl. 214-77) This invention relates to tail gate mechanismsfor trucks and the like and more particularly to a power-operatedmechanism for raising and lowering a tail gate serving as a platform orelevator for lifting and lowering heavy articles which are to be loadedupon or removed from the truck, the gate not only serving as a loadingplatform but also as a closure for the rear end of the truck body andincluding in its construction an auxiliary gate or port gate which ismounted for independent'opening or closing movement and thus allowed tobe swung to an opened position while the main gate is in a raised andclosed position.

The present application constitutes a division from my copendingapplication filed July 25, 1951, and having Serial No. 23 8,443 and nowPatent No. 2,683,545 granted July 13, 1954.

One object of the invention is to provide tail-gate operating mechanismwhich is power operated and has improved means for controlling raisingand lowering of the tail-gate and opening and closing of the auxiliaryport gate, the operating mechanism being controlled by a lever actuatedby the person having charge of the truck.

Another object of the invention is to provide a novel mechanism forautomatically holding the control lever and associated mechanism in anoperating position as desired until mechanically or manually changed andthus eliminate the necessity of having to hold the control lever whenoperating the tail gate.

Another object of the invention is to provide improved tail-gateoperating mechanism which is simple in construction, easy to operate,and capable of withstanding rough usage without being broken orotherwise damaged.

With these and other objects in view, the invention consists of a novelconstruction and arrangement of parts hereinafter fully described,illustrated in the accompanying drawings and set forth in the appendedclaims, it being understood that the various changes in form,proportions and details of construction within the scope of the claimsmay be resorted to without departing from the spirit of the invention orsacrificing any of the advantages gained thereby.

In the accompanying drawings:

Fig. 1 is a side elevation showing the rear portion of a truck with thetail-gate in a lowered position;

Fig. 2 is a view similar to Fig. 1 showing the tail-gate flush with thefloor of the truck;

Fig. 3 shows the tail-gate closed;

Fig. 4 is a side elevation showing the truck body tilted to a dumpingposition and the port gate released and swung outwardly to its releasedposition;

Fig. 5 is a perspective view showing the rear portion of the truck withthe tail-gate lowered and in the position shown in Fig. 1;

Fig. 6 is a rear view of the truck;

Fig. 7 is a side elevation looking at one side of the truck with thetailgate in its lower position;

Fig. 8 is a view looking at the other side of the truck with thetail-gate level with the floor of the truck;

Fig. 9 is a fragmentary plan view upon an enlarged scale showing themechanism for operating the tail-gate;

Fig. 10 is a sectional view taken vertically along the line 10-10 ofFig. 9;

Fig. 11 is a similar view taken along the line 11 -11 of Fig. 9;

Fig. 12 is a viewpartially in elevation and partially in section showingupon an enlarged scale an adjustable pre-loaded valve centeringmechanism for holding a valve in a desired operating position untilmanually or mechanically'released;

Fig. 13 isan end view of Fig. 12.

In the accompanying drawings, in which is illustrated one embodiment ofthe invention, the dumping truck is provided with a dumping body 1provided at opposite sides of its rear end with depending bearingbrackets 2 constructed of any suitable material such as flanged metal,consisting of a vertical upper oblong portion 3 and a tapered inclinedlower portion ,4 extending downwardly and forwardly and provided at itslower end with a bearing 5. The bearings of the brackets 2 receive andhave journaled in them for rotary movement an outer transverse rockablehollow shaft 6 which has journaled within it for rotary movement aninner transverse rockable shaft 7. The outer transverse shaft 6 isjournaled in suitable bearings 8 of bearing brackets 9 located atopposite sides of the truck and secured to the chassis 10 thereof andthe lower portions 11 of the bearing brackets 9 extend downwardly andforwardly at an inclination from the upper attached portions 12 of thebearing brackets 9;

The dumping body which pivots on the outer shaft .6

is tilted from the horizontal position illustrated in Figs. 1 to 3,inclusive, to the inclined position shown in Fig. 4 by the usualhydraulically operated means including spaced cylinders 13 located atopposite sides of the chassis of the truck and arranged at aninclination and pivoted at their lower ends at 14 to depending bearingbrackets 15 secured to the chassis of the truck,'as clearly illustratedin Figs. 1 to 4, inclusive. The piston 15 of each cylinder 13 ispivotally connected at 16 to the dumping body at the bottom thereofbelow the upper face of the floor of the same. The hydraulic power meansfor operating the dumping body is of the usual conventional means and isvalve controlled within the cab of thetruck and further illustration anddescription of the power meansfor operating the dumping body arebelieved to be un necessary as the dumping body operates in the usualmanner and is tilted from its normal horizontal position to an inclineddumping position and automatically returns to its initial horizontalposition after the discharge of its contents when the piston 15'isrelieved of hydraulic pressure in the. usual manner.

The particular means for pivotally mounting the dump- Details oftail-gate raising and lowering mechanism While the invention is directedprimarily to a poweroperated tail-gate capable of being applied to adumpbody and provided with an independently operable dumping inner orport-gate 18 in the main tail-gate 17, it also includes a number offeatures that cooperate to make such a combination operablesatisfactorily. In my pre- Patented Oct. 4, 1955 ferred embodiment ofthis invention the tail-gate raising and lowering mechanism on the onehand and on the other hand the tail-gate operating mechanism to move itbetween horizontal and vertical positions, both function from saidduplex operating shaft that has one shaft concentrically arranged withinthe other in a way that rotation of the outer shaft causes the raisingand lowering of the power tail-gate while the rotation of the innershaft causes movement of the tail-gate between the horizontal andvertical. So, in obtaining the object of this invention, this duplexshaft that extends transversely of the truck must be operativelysupported from the truck chassis at an elevation below the top of thechassis and sufiiciently inboard from the tail-gate so that there is nointerference of these mechanisms with the full dumping operation of thetruck body and the tail-gate. This is accomplished by the angle orknee-shaped brackets 2 which must be long enough to provide for thesupport of a cylinder 19 and its mechanism for swinging the tailgatebetween horizontal and vertical while at the same time makingunnecessary too long a reach between the inner of the concentric shaftsand the tail-gate.

The outer shaft 6 is provided at its central portion with a pair of arms20 extending upwardly and rearwardly at an inclination when thetail-gate is in its lowered position, as illustrated in Fig. 5, andhaving secured between their outer ends by a pivot 21 the outer end of apiston 22 of a cylinder 23 arranged at an inclination and extendingdownwardly and rearwardly from the truck body 1 and connected at itsupper end to the same by a suitable pivot 24 at a point below the upperface of the bottom of the truck body.

The outer shaft 6 is also provided adjacent its ends with a pair oflifting arms 25 rigidly connected with the outer shaft 6 whichpreferably comprises I-beams or other suitable material having therequired strength. The lifting arms 25 are provided at their outer endswith plates 25 rigidly secured to the lifting arms in any suitablemanner and connected at their outer ends with the tail-gate adjacent thelower edge thereof by a pivot 26. When pressurized fluid is introducedinto the cylinder 23 for actuating the piston 22, the outer shaft isrotated for oscillating the lifting arms 25 for lowering the tail-gatefrom a horizontal position level with the floor of the truck body to theground and for elevating the tail-gate to return it from its groundposition to its elevated'position flush with the floor of the body 1 ofthe truck for enabling a load to be lifted from the ground and readilytransferred into the truck body. The lifting arms 25 swingthrough an areindicated by the dot-and-dash line 270i Fig. 7 and the tail-gate iscarried in a substantially horizontal position from one point to theother and vice versa, and it constitutes a platform on which theoperator may stand while the load is being transferred from the groundto the body of the truck or from the truck to the ground.

T ail-gate swinging mechanism and operation The. pivot 26 preferablyconsists of a transverse shaft journaled in suitable eyes 28 of thetail-gate and it constitutes a. pintle on which the tail-gate swings inlowering it from a vertical closed position to the open horizontalposition illustrated in Fig. 2. of the drawings and indicated by dottedlines in Fig. 7'. The enlarged ends 23 of. the inner shaft are extendedbeyond the ends of the outer shaft and are provided with terminaloppositely extended radially disposed arms 30 which are connected. bypivots 31 to the adjacent ends of the. pair of spaced parallel links 32preferably consisting of flat bars connected by pivots 33 to the hingedlower edges of the tail-gate at opposite sides of the pintle or pivotshaft 26. The inner shaft is adapted to be rotated to carry the arms 30through an arc of approximately 45 and this motion is transmitted by theparallel links 32 to the tail-gate which isadapted to beswung downwardlyfromthe closed position shown in Fig. 3 to the horizontal position shownin Fig. 2 and also to be swung upwardly from the horizontal positionshown in Fig. 2 to its vertical closed position shown in Fig. 3. Anyother suitable link connection may, of course, be provided fortransmitting motion from the inner shaft to the tail-gate for swingingthe same on its horizontal shaft or pintle 26.

This rotary movement of the inner shaft 7 is effected by a piston 34operating in the cylinder 19 extending longitudinally of one of theangle bearing brackets 2 of the body 1 and arranged at a slightinclination and connected at its upper end by a suitable pivot 35 to thebracket 2 on which it is mounted.

The lower end of the piston 34 is connected by a pivot 36 to an anglearm 37 fixed to the adjacent outer extended end of the inner shaft 7 andextending downwardly and rearwardly therefrom, as clearly illustrated inFig. 7 of the drawing.

The tail-gate 17 and the dump or port-gate 18 are operable as a unit inswinging the tail-gate from a vertical to a horizontal position to openit, and also when lowering the tail-gate from an elevated horizontalposition contiguous to the floor of the body of the truck to the groundand while elevating the tail-gate to said horizontal position and alsowhile swinging the tail-gate from said horizontal position to itsvertical closed position. The tailgate unit comprises a frame composedof spaced parallel side portions 38 and a connecting bottom portion 39and the dump or port-gate consists of a panel connected at its upperedge to the upper ends of the sides 38 by suitable pivots 40, but thepanel may be pivoted within the frame of the tail-gate in any othersuitable manner. The

inner edges of the sides 38 and the connecting bottom portion 39 of theframe of the tail-gate are arranged flush with the inner faces of theside walls of the body and thebottom of the body when the tail-gate isclosed so that when the body is dumped and the port-gate is unlatched,the entire contents of the body of the truck may be discharged throughthe opening in the tail-gate without any interference of the frame ofthe tail-gate to the complete discharge of the contents of the truck.

Hydraulic system and valve control mechanism valve 41 communicates byhydraulic lines 45 and 46 with the spaces between the ends of thecylinder 19 and the piston 34 which is connected to theinner shaft 7;The

other valve 42 is connected by the hydraulic line 48 with; the cylinder23 and the piston 22 which is connected with;

the outer shaft 6. I

The valves 41 and 42 which may beof any preferred type are preferablyconstructed substantially the sameas. shown and described inmy priorPatent 2,469,321 and when the valve stems 49 and 50 are moved inwardlyto the limit of their inward movement they open thevalves to connect thecylinders 19 and 23 to the pump and when the valve stems are carried tothe limit of their outward movement communication between the cylinders19 and 23 through the hydraulic lines 45 and 48 with the pump is cut offand the hydraulic lines are placed in communication with a sump forexhausting pressurized fluid from the cylinders and at the same timeadmitting pressurized fluid to the other end of the cylinder 19 through.the hydraulic line 46 for returning the piston to itsinitial thecylinders 19 and 23 and maintain a fluid look within the cylinders.

It will be understood, as explained in said Patent 2,469,321, that the.operation of the valve 42 prevents any passage of fluid to thevalve 41.Thestem49. of the.

valve 41 may be moved inwardly simultaneously with a similar movement ofthe stem 50 of the valve 42, but it is only upon outward movement of thelatter stem to its outward position that pressurized fluid may flowthrough the valve to the cylinder 23. Thus the cylinders 19 and 23 maybe operated independently of each other but not simultaneously.

The valve stem 49 is connected by a link rod 51 with an arm 52 of atransverse control or operating rock shaft 53 journaled in suitablebearings of the frame of the truck body and extending transverselythereof from one side of the truck body to the other side of the sameand provided at each end with an operating handle 54. The operatinghandles 54, which are approximately L-shaped, extend at each side of thetruck body to points within easy reach of a person standing at the sideof the truck.

The valve stem 50 of the valve 42 is connected by a link rod 55 with aninner depending arm 56 of a transverse rock shaft 57 journaled insuitable bearings of the truck body frame and provided with an outerdepending arm 58. The outer depending arm 58 is connected by a link rod59 with a depending arm 60 of an operating shaft 61 journaled insuitable bearings of the frame of the truck body and extending acrossthe same and provided at each end with an upwardly extending operatingarm or handle 62. The control mechanism for operating the valve stem 50of the valve 42 is adapted to be operated from either side of the truck.

When the control-valve 42 is operated to introduce pressurized fluidinto the cylinder 23 for elevating the tailgate from the ground positionshown in full lines in Fig. 6 to its dotted line position illustrated insaid figure, wherein the tail-gate is still in its horizontal positionbut flush with the floor of the body of the truck, the tail gate isautomatically stopped in the dotted line position by means operable bythe outer shaft 6 to which the lifting arms are connected. The rockshaft 57 is slidably held in the guide member 103 through which thefront end of the rod 101 passes, as shown in Fig. 10. The rear end ofthe rod 101 is connected to a crank or lever arm 104 arranged in anupright position on the shaft 104*, which is suitably journaled in bodyhinge. The rod 101 and the arm 104 are movable rearwardly from theposition illustrated in Fig. of the drawings. Adjacent the arm 104 andcarried by the shaft 104 is an adjustable abutment screw 115 which iscontacted by one of the lifting arms when the gate reaches the raisedhorizontal po-' sition shown indicated by dotted lines in Fig. 7. Theshaft 104 is rotated counterclockwise upon the lifting arm 25 strikingthe screw 115. This causes forward longitudinal movement of the rod 101beyond the position illustrated in Fig. 10 for enabling the coil spring100 to bias the arm 67 and the rock shaft 57 in the position illustratedby dotted lines in Fig. 7. The spring permits rearward movement of thearm 67 and partial rotation of the rock shaft 57 from the dotted lineposition illustrated in Fig. 7 in the operation of the valve 42. Thespring 100 and the rod 101 are adapted to yield to the movement of thearm 67 when the handle lever 62 is operated. Adjustment of the abutmentscrew 115 is made so that it will be engaged and the rod 101 actuated toshut off the flow of pressure fluid to cylinder 23 whereby the tailgateis accurately aligned with the floor of the truck when in its dottedline raised position as shown in Fig. 7.

The lifting arms 25 are provided at their outer portions adjacent thetail-gate with lugs 79 arranged to be engaged by a pair of pivotallymounted gravity acting catches 80 arranged in the path of the lugs 79.When the lifting arms are swung upwardly to a vertical position they areautomatically locked in such position to prevent the tail-gate fromdropping should there be any release or failure of the hydraulic means.When the tail-gate is swung upwardly from its elevated horizontalposition flush with the floor of the truck body to its vertical closedposition it is automatically locked thereof and extending through guides82 and arranged to engage shouldered lugs 83 located at the oppositeside edges of the tail-gate at the upper portions of the sides 38 of theframe of the tail-gate. This assures positive support for the gate whendumping. Any suitable'latch means may be provided for releasably holdingthe portgate 18 closed.

Rock shaft 53 is provided with a pair of oppositely extending arms 68and 69 pivotally connected at 70 and 71 to the upper ends of a pair ofoperating rods 72 and 73-having their lower end portions slidable inguides'74 and 75 carried by one of the bearing brackets 2and ar rangedto be engaged by abutment-forming lugs 76 and 77 projecting radiallyfrom the enlarged ends 29 of the inner shaft 7. As the tail-gateapproaches its vertical position the lug 76 engages the lower end of theoperating rod 73 and shifts the rock shaft 53 so as to operatethe' valve41 and cut off pressure fluid to prevent further movement of the tailgate. Also when the valve 41 is operated to open the tail-gate from thedotted line position shown in Fig. 6 to the horizontal position, the lug77 of the enlarged end 29 of the inner shaft 6 engages the lower end ofthe operating rod 72 and operates the valve 41 to prevent further rotarymovement of the outer shaft. The operating rods 72 and 73 are providedat their upper ends with sections 78 having a threaded connection withthe rods for adjusting the same for enabling the valve 41 to beaccurately operated.

Details of kick-out valve control mechanism and operation trated in Fig.12 in connection with the operation of valve 42. it will be understoodthat valve 41 is equippedwith a kick-out control mechanism similar tothat used for valve 42 and operates in the same manner. The mechanism asillustrated in Fig. 12, comprises an elongated'tubular housing having acentral bore 121 extending lengthwise therethrough and arranged toslidably receive a spool-valve shaft 122. The shaft 122 extendsoutwardly from the housing 120 and is attached at its'outer end throughan arm 124 to'the end of the valve shifting rod 50, as shown at 126. Theshaft 122 has a reduced diameter portion 128 which extends through anenlarged diameter spring chamber 130. the reduced diameter shaft portion128 and is retained under compression between the washers 132 and 133.The

washers are slidably fitted in the chamber 130 and are adapted to bemoved axially of the shaft to compress the spring 131 upon shifting ofthe shaft 122.

On the outer end of the reduced diameter portion 128 of the shaft ismounted a sleeve 136 adapted to slide in the bushing 138 which issecured in the end portion of the spring chamber 130. A stub bolt'140isreceived on the outer end of the shaft and is threaded down against awasher 141 whereby the sleeve 136 is retained in place on the shaftbetween the washers 133 and 141.

On the enlarged diameter portion of the shaft 122 thereis providedspaced circumferential grooves 145; 146 and 147 which are adapted toreceive a spring-pressed ball 150. The lower end of the spring 154 restson the ball detent 150, the ball being of a diameter to fit snugly intoI A coil spring 131 surrounds the annular grooves 145, 146, 147 on thespool-valve 122. To provide foradjusting the spring load on the balldetent 150, the upper end of the casing 152 is threaded to receive ahollow set screwmember 158 which may be threaded downwardly to vary theload on the coil spring 154. The upper end of the casing 152 of the balldetent mechanism is suitably closed by a cap 166 which is threaded onthe end of the casing, as illustrated in Fig. 12. A grease cup 161issuitably mounted on the cap 169 for conveniently applying lubrication tothe ball detent 150.

The valve kick-out lever release assembly is suitably supported on thespaced leg members 166 which in turn are welded to the lower portion ofthe casing 120. The

leg supports 166 are adapted to rest on a base plate 168 suitablymounted on the top of the valve assembly 42, as illustrated'in Figs. 12and 13.

-The setting of the rod 126, which is operatively connected to the rod50 and forms an extension thereof, is yieldably maintained in either oneof three positions by the adjustable spring loaded ball detent 150. Thuswhen the valve rod 50 and its counterpart 126 are shifted as by manuallymoving the lever 62, so as to slide the valve rod, for instance, to theleft, as seen in Figs. 11 and 12, the arm 124 attached to the end of therod 126 carries the shaft 122 to the left so that the ball detent 150 isforced out of its center groove position, representing the neutral orfluid lock position, and upon further movement of the shaft 122, dropsinto the annular groove 147, where the parts are maintained during theoperation of the hydraulic lift. The spring 154 of the ball detent isadjustably loaded, as aforementioned, by turning down the screw member158 so that the spring load on the ball detent is just sufiicient toovercome the force exerted by the compression spring 131 and which tendsto return the shaft 122 to its center or fluid lock, safety position.Under this action of the spring loaded ball detent, it is unnecessaryfor the operator to hold his hand on the control lever for operating thehydraulic valves after the lever is moved either to the right or left,to start the desired power movement of the tail-gate mechanism.

. As the end of the particular cycle of operation initiated by movementof the lever 62 or 54, the valve control rod to which the hand lever isoperativ'ely connected is manually shifted or mechanically engaged sothat the ball detent 150- is forced out of its seat in the groove andthe spring 130 is then permitted to return the shaft 122 to its normalcenter groove which represents the fluid lock, safety position. In thisposition all movement of the parts is stopped instantly and maintainedin their relative positions. This kick-out mechanism thus providesfingertip control so that the tail-gate can be stopped instantly and atany intermediate position desired.

The coil spring 100 mounted on the rod 101 and interposed between acollar 102 on the rod and an arm member 67 of the rock shaft 57 permitslost motion between the parts whereby the manually operated controllever 62 can remain in a set position until manually moved or itsconnecting control rod mechanism shifted automatically by engagementtherewith of a portion of the tail-gate mechanism being moved to therebycause the shaft 122 to shiftand release the ball detent from theoperative position whereby the same is shifted by the coil spring 131 toitsneutral, fiuid lock, safety position and all movement of the partsceases. The same action takes place upon actuationof the control lever54 which is also provided with a similar spring actuated ball detentkick-out lever release mechanism and as shown in Fig. 11 by the primereference characters and corresponding to the reference charactersdesignating the described parts for operating the valve 42.

The, catches 80 which are located at opposite sides of theframe of thetruck body, are mounted on short shafts 10 8. journaled in suitablebearings of brackets 109 and provided witharms 110 which are connectedby short links 111 to arms 112 of a transverse rock shaft 113 which isconnected by a link rod 114 with the arm 67 of the rock shaft 57 wherebythe catches 80 will be lifted out of engagement with the lugs 79 byoperation of the lever 62.

While the preferred embodiment of the invention has been shown anddescribed, it is to be understood that this embodiment may be modifiedas to the details within the spirit and scope of the invention and ascovered by the appended claims.

What is claimed is:

1. A truck having a wheeled chassis with a superposed body having afloor provided with a tailgateas well as tailgate lowering and raisingmeans supported from the chassis and including an outer rockable hollowshaft having laterally extending arms fixed thereto for supporting thetailgate, hydraulic means for rocking the shaft to lower and to raisethe tailgate having a pistonbearing cylinder in a pump-motivatedhydraulic circuit as well as reciprocable spool-valve means forcontrolling the direction of motion of the piston, manually operablemeans both for motivating the hydraulic means and for moving thedirection-controlling spool-valve to a position whereby the pistonthrough the shaft and its arms either lowers or raises the tailgate,automatic means having an interposed spring-biasing connection andoperated by. at least one of the arms on the shaft when it approachesfull raised position for moving the spool-valve toward piston-stoppingposition, and spring-tensioned detent means operable on the spool-valveas the biased spring moves the spool-valve past the detent to detain thespool-valve in neutral position to stop further movement of the pis-vton and consequently to stop the raising movement of the tailgate at thelevel of the truck bodys floor.

2. A truck having a wheeled chassis with a superposed body having afloor provided with a tailgate as well as tailgate lowering and raisingmeans together with means not only for pivotally opening the tailgate tohorizontal position but for pivotally closing it to vertical positionwith both said means supported from the chassis, the

lowering and raising means including an outer rockable hollow shafthaving laterally extending arms fixed thereto for supporting thetailgate, hydraulic means for rocking the shaft to lower and to raisethe tailgate, manually operable means for motivating the hydraulicmeans, and automatic means for stopping the rising tailgate at the levelof the truck bodys floor; while the tailgate opening and closing meansinclude an inner rockable shaft projecting through the outer rockableshaft while carrying enlarged ends provided with lug means and a pivotedline connection between the inner shaft and the body-abutting side ofthe tailgate, hydraulic means for rocking the inner' shaft having apiston-bearing cylinder in a pump-moth vated hydraulic circuit as wellas spool-valve means for controlling the direction of motion of thepiston, manually-operable means both for motivating the hydraulic meansand for moving the spool-valve toward pistonstopping position, automaticmeans including lever means engageable by the lugs on the enlarged endsof the rockable inner shaft when that shaft approaches the limits of itsrocking path, and spring-tension detent means operable on thespool-valve during engagement by the lugs with the lever means to detainthe spool-valve in neutral position to stop further movementrof thepiston and consequently to stop the pivotal movement of the tailgateeither at its vertical or at its horizontal position as the case: maybe.

3. A truck having a wheeled chassis with a superposed:

body having a floor provided with a tailgate as well as tailgatelowering and raising means together with means not only for opening thetailgate to horizontal position but for closing the tailgate to verticalposition withboth said means supported from the chassis; the loweringand raising means including an outer rockable hollow shaft havinglaterally extending arms fixed thereto for suppprt;v

ing the tailgate, a first hydraulic means forrocking the shaft to lowerand to raise the tailgate having alfi, a

piston-bearing cylinder in a first pump-motivated hydraulic circuit aswell as a first reciprocable spool-valve means for controlling thedirection of motion of the first piston, manually operable means bothfor motivating the first hydraulic means and for moving the firstspool-value to a position whereby the first piston through the outershaft and its arms either lowers or raises the tailgate, first automaticmeans having an interposed spring-biasing connection and operated by atleast one of the arms on the shaft when it approaches full raisedposition for moving the first spool-valve toward piston-stoppingposition, and springtensioned detent means operable on the firstspool-valve as the biased spring moves that spool-valve past the detentto detain that spool-valve in neutral position to stop further movementof the piston and consequently to stop the raising movement of thetailgate at the level of the truck bodys floor; the tailgate opening andclosing means including an inner rockable shaft projecting through theouter rockable shaft while carrying enlarged ends each provided with lugmeans and a pivoted link connection between the inner shaft and thebody-abutting side of the tailgate, second hydraulic means for rockingthe inner shaft having a second piston-bearing cylinder in a secondpump-motivated hydraulic circuit as well as a second spool-valve meansfor controlling the direction of the second piston, a secondmanually-operated means both for motivating the second hydraulic meansand for moving the second spool-valve toward piston-stopping position, asecond automatic means including a lever engageable by the lugs on theenlarged ends of the rockable inner shaft when that shaft approaches thelimits of its rocking path, and a second spring-tensioned detent meansoperable on the second spool-valve during engagement by the lugs withthe lever means for detaining that spool-valve in neutral position tostop further movement of the second piston and consequently to stop thepivotal movement of the tailgate either at its vertical or itshorizontal position as the case may be.

4. A truck having a wheeled chassis with a superposed body having afloor provided with a tailgate as well as tailgate lowering and raisingmeans supported from the chassis and including a rockable shaft havinglaterally extending arms fixed thereto for supporting tailgate,hydraulic means for rocking the shaft to lower and to raise the tailgatehaving a piston-bearing cylinder in a pumpmotivated hydraulic circuit as well as reciprocable spoolvalve means for controlling the direction ofmotion of the piston, said spool-valve means being spring biased toneutral position wherein the motion of the piston is stopped, means formotivating the hydraulic means, and manually operable means for movingthe direction-controlling spool-valve to a position whereby the pistonthrough the shaft and its arms either lowers or raises the tailgate,means forming an abutment fixed on said shaft, automatic means operatedby said abutment when the arms on said shaft approach full raisedposition for moving the spool-valve toward neutral position, and springtensioned detent means operable on the spool-valve as the automaticmeans and the valve biasing spring move the spool-valve past the detentto detain the spool-valve in said neutral position to stop furthermovement of the piston and consequently to stop the raising movement ofthe tailgate at the level of the truck bodys floor.

References Cited in the" file of this patent UNITED STATES PATENTS2,265,260 Argo Dec. 9, 1941 2,362,671 Schwan Nov. 14, 1944 2,471,285Rice May 24, 1949 2,570,896 Winchester Oct. 9, 1951 2,572,705 Edman Oct.23, 1951 FOREIGN PATENTS 426,333 Great Britain Apr. 2, 1935

